Faced with a staggering increase in families lining up for food each week, the United Way of Tri-County is launching a new fund-raising campaign as it tries to keep up with rising demand.

The regional agency, which runs food pantries in Framingham, Marlborough, and Clinton serving more than two dozen area communities, has started the Feed-A-Family for Fifty Campaign, which seeks $50 donations to provide households in need
with a turkey dinner and fixings for Thanksgiving and the holiday season. It hopes to raise enough money to feed 3,000 families.

Paul Mina, president of the Framingham-based agency, said cash donations have not kept pace with increased demand over the past year, and officials are worried that some families will go hungry.

“The food pantries have seen dramatic increases in usership,’’ Mina said. “It’s been very disturbing. We can’t keep up with the increases.’’

The number of families using the pantry at Pearl Street Cupboard and Cafe in Framingham increased from 250 in January to 1,800 in September, for a 700 percent increase in just nine months, according to the agency. In Marlborough, the numbers went from 25 to 50 families.

The number of individuals and families receiving hot meals at the organization’s facility in Framingham has more than doubled over the past six months.

The trend is the same in other area communities, including Milford and Waltham, where food pantries are trying to stock up for the holiday season. In Acton, however, the numbers have stabilized for the first time in several years, said Donna Bottari, the food pantry director of the Acton Community Supper and Food Pantry Inc.

Bottari said she’s not sure why, but is happy the numbers didn’t rise this year.

“They were increasing for a number of years so it’s nice to see it steady,’’ Bottari said. “We’re at our capacity right now.’’

Bottari said the pantry helps about 200 households in the Acton and Boxborough area each week.

The news isn’t as positive in Waltham, where the need continues to grow, said Joe Attardo, coordinator of the Sacred Heart Church Food Pantry
.

Attardo said the pantry used to provide groceries to 50 families each week, and now it’s capped at 100.

“We can’t keep up with it,’’ Attardo said. “Sometimes we end up turning people away. It’s disheartening.’’

David L Ryan/Globe Staff Photo

People "shopping" for food at Brookline food pantry at St Paul's Episcopal Church and about increased demand at area food pantries.

Attardo said the pantry gave out turkeys last year for Thanksgiving, but won’t do it again this holiday because the demand was overwhelming. He said people were lined up for blocks, and the police had to be called in to help keep order.

Attardo said it’s also difficult to keep up with demand because fewer people are able to help out.

“Donations are down because people are low on cash,’’ Attardo said. “There’s no extra income for them to part with.’’

At the Salvation Army Food Pantry in Milford, there is a 12 percent increase in the number of applications for Thanksgiving dinners.

“It’s not just the unemployed, it’s people who have one and two jobs,’’ said Jessica Irwin, a top official at the Salvation Army’s Milford location.

Mina, of the United Way, said he is also seeing an increase in the number of working families seeking help.

In past years, the food pantries would typically help the homeless, unemployed, and mentally ill, he said.

“Now we get the unemployed and, worse, the underemployed, people who go to work every day but they don’t make enough to make ends meet,’’ Mina said.

“They can work their tails off and still not come close. The face of hunger in our area is changing dramatically.’’

To help those in need, Mina is encouraging those who can to forgo one extra present or dinner out this holiday season and instead donate $50, which would feed a family of four for the holidays, or provide as many as seven bags of groceries from one of its three food pantries. The agency hopes to serve at least 3,000 families this year.

“A little donation like $50 could make a huge difference,’’ Mina said. “It’s going 100 percent to buy food for the hungry.’’

In addition, the United Way of Tri-County and MetroWest Regional Transit Authority are teaming up for the Food for Fare program. It is a campaign to encourage MWRTA riders to donate nonperishable canned or boxed food on Monday and Tuesday, and in exchange ride the bus for free.

“We’re not going to be able to help everybody, but we’ll help some,’’ Mina said.